City lost 2-0 to Barça at the Etihad after goals from Lionel Messi and Dani Alves. Messi's came from a penalty that Pellegrini disputed, with Eriksson also sending off Martín Demichelis, who made the challenge on his countryman.

Pellegrini claimed that Eriksson failed to be impartial and had decided from the start to rectify mistakes he made in a previous Champions League tie involving the Spanish club and Milan.

Uefa is awaiting reports from Eriksson and the match delegate, who have until Thursday evening to file them, before deciding whether to charge Pellegrini, who would likely be issued with a touchline ban for the Camp Nou.

Of City's prospects of overcoming Barça on 12 March, Nasri said: "We will have to gamble, but why not? We went to [Bayern] Munich and beat them [in the group stage], so we can do the same.

"The referee [went wrong]. There was a foul on Jesús Navas first – we saw the footage and it was not a penalty. It is really frustrating this decision, because before it was a close game. They did not have any clear chances, but it is not over. We can do it. It will be an open game, they will come like Barcelona.

"They will come and play, so we will have plenty of space. [Sergio] Agüero will be back, we will be fitter, so why not? It does not change anything in our belief and our quality. We believe in ourselves. We believe in what we can do.

"At the start of the season, we won at Munich. We won at home to Manchester United and Spurs, and by big scores."

Given the away-goals rule, and City having to score at least three times, they could allow Gerardo Martino's team to net at least once. "Everything is possible. Thee-one? We can do it," said the Frenchman.

Nasri believes City can be encouraged by Valencia's 3-2 win at the start of month. That was Barça's first home defeat of the campaign. "They played without fear. That is what we need to do. We have to gamble, try to play and attack them. They do not like to be attacked," he said.

Nasri, who came on as a second-half replacement, is clear that City were not scared of Barça. "When it is a big game like this the two teams are there like boxers in the first round, trying to see how your opponent is," he said. "After that, we started to press them high and we saw they were like any team. They lose the ball. That is what we need to do."

The playmaker maintains that Barça are not the best side City have played this season. "No, I don't think they are," he said, then cited the holders' 3-1 win at the Etihad during the group stage. "Bayern are the best team we played here. Against Bayern, for 60 minutes we did not touch the ball.

"They are the best team, Barcelona are not. If it was not for the penalty, it was 0-0. Bayern was not the same. We did not touch the ball, they scored goals without a mistake from anyone. They showed us how great they were. I am convinced that Bayern are the best team we have played against."

With City's hopes of an unprecedented quadruple now appearing unlikely, Nasri, left, is intent that focus will be maintained on the other competitions. "Don't worry. We turn the page already and we are focused on the Stoke game and the Capital One Cup final," he said of Saturday's league meeting and next month's Wembley game with Sunderland.

Jim Boyce, a Fifa vice-president who is chairman of the governing body's referees committee, rejected Pellegrini's criticism of Tuesday night's referee. The Chilean had also claimed that as a Swede Eriksson should not have officiated such a high-level game as "there was more important football in Europe".

Yet Boyce said: "It is absolute nonsense to say a referee should not be chosen for an important match because he comes from a smaller country. If the referee has proved himself at the top level it should not matter what country they come from."